This invention relates generally to methods and apparatus for attaching soft tissue to bone, and more particularly to anchors and methods for securing connective tissue, such as ligaments or tendons, to bone. The invention has particular application to arthroscopic surgical techniques for reattaching the rotator cuff to the humeral head, in order to repair the rotator cuff.
It is an increasingly common problem for tendons and other soft, connective tissues to tear or to detach from associated bone. One such type of tear or detachment is a xe2x80x9crotator cuffxe2x80x9d tear, wherein the supraspinatus tendon separates from the humerus, causing pain and loss of ability to elevate and externally rotate the arm. Complete separation can occur if the shoulder is subjected to gross trauma, but typically, the tear begins as a small lesion, especially in older patients.
To repair a torn rotator cuff, the typical course today is to do so surgically, through a large incision. This approach is presently taken in almost 99% of rotator cuff repair cases. There are two types of open surgical approaches for repair of the rotator cuff, one known as the xe2x80x9cclassic openxe2x80x9d and the other as the xe2x80x9cmini-openxe2x80x9d. The classic open approach requires a large incision and complete detachment of the deltoid muscle from the acromion to facilitate exposure. The cuff is debrided to ensure suture attachment to viable tissue and to create a reasonable edge approximation. In addition, the humeral head is abraded or notched at the proposed soft tissue to bone reattachment point, as healing is enhanced on a raw bone surface. A series of small diameter holes, referred to as xe2x80x9ctransosseous tunnelsxe2x80x9d, are xe2x80x9cpunchedxe2x80x9d through the bone laterally from the abraded or notched surface to a point on the outside surface of the greater tuberosity, commonly a distance of 2 to 3 cm. Finally, the cuff is sutured and secured to the bone by pulling the suture ends through the transosseous tunnels and tying them together using the bone between two successive tunnels as a bridge, after which the deltoid muscle must be surgically reattached to the acromion. Because of this maneuver, the deltoid requires postoperative protection, thus retarding rehabilitation and possibly resulting in residual weakness. Complete rehabilitation takes approximately 9 to 12 months.
The mini-open technique, which represents the current growing trend and the majority of all surgical repair procedures, differs from the classic approach by gaining access through a smaller incision and splitting rather than detaching the deltoid. Additionally, this procedure is typically performed in conjunction with arthroscopic acromial decompression. Once the deltoid is split, it is retracted to expose the rotator cuff tear. As before, the cuff is debrided, the humeral head is abraded, and the so-called xe2x80x9ctransosseous tunnelsxe2x80x9d, are xe2x80x9cpunchedxe2x80x9d through the bone or suture anchors are inserted. Following the suturing of the rotator cuff to the humeral head, the split deltoid is surgically repaired.
Although the above described surgical techniques are the current standard of care for rotator cuff repair, they are associated with a great deal of patient discomfort and a lengthy recovery time, ranging from at least four months to one year or more. It is the above described manipulation of the deltoid muscle together with the large skin incision that causes the majority of patient discomfort and an increased recovery time.
Less invasive arthroscopic techniques are beginning to be developed in an effort to address the shortcomings of open surgical repair. Working through small trocar portals that minimize disruption of the deltoid muscle, a few surgeons have been able to reattach the rotator cuff using various bone anchor and suture configurations. The rotator cuff is sutured intracorporeally and an anchor is driven into bone at a location appropriate for repair. Rather than thread the suture through transosseous tunnels which are difficult or impossible to create arthroscopically using current techniques, the repair is completed by tying the cuff down against bone using the anchor and suture. Early results of less invasive techniques are encouraging, with a substantial reduction in both patient recovery time and discomfort.
Unfortunately, the skill level required to facilitate an entirely arthroscopic repair of the rotator cuff is inordinately high. Intracorporeal suturing is clumsy and time consuming, and only the simplest stitch patterns can be utilized. Extracorporeal knot tying is somewhat less difficult, but the tightness of the knots is difficult to judge, and the tension cannot later be adjusted. Also, because of the use of bone anchors to provide a suture fixation point in the bone, the knots that secure the soft tissues to the anchor by necessity leave the knot bundle on top of the soft tissues. In the case of rotator cuff repair, this means that the knot bundle is left in the shoulder capsule where it can be felt by the patient postoperatively when the patient exercises the shoulderjoint. So, knots tied arthroscopically are difficult to achieve, impossible to adjust, and are located in less than optimal areas of the shoulder. Suture tension is also impossible to measure and adjust once the knot has been fixed. Consequently, because of the technical difficulty of the procedure, presently less than 1% of all rotator cuff procedures is of the arthroscopic type, and is considered investigational in nature.
Another significant difficulty with current arthroscopic rotator cuff repair techniques is shortcomings related to currently available suture anchors. Suture eyelets in bone anchors available today, which like the eye of a needle are threaded with the thread or suture, are small in radius, and can cause the suture to fail at the eyelet when the anchor is placed under high tensile loads.
There are various bone anchor designs available for use by an orthopedic surgeon for attachment of soft tissues to bone. The basic commonality between the designs is that they create an attachment point in the bone for a suture that may then be passed through the soft tissues and tied, thereby immobilizing the soft tissue. This attachment point may be accomplished by different means. Screws are known for creating such attachments, but existing designs suffer from a number of disadvantages, including their tendency to loosen over time, requiring a second procedure to later remove them, and their requirement for a relatively flat attachment geometry.
Another approach is to utilize the difference in density in the cortical bone (the tough, dense outer layer of bone) and the cancellous bone (the less dense, airy and somewhat vascular interior of the bone). There is a clear demarcation between the cortical bone and cancellous bone, where the cortical bone presents a kind of hard shell over the less dense cancellous bone. The aspect ratio of the anchor is such that it typically has a longer axis and a shorter axis and usually is pre-threaded with a suture. These designs use a hole in the cortical bone through which an anchor is inserted. The hole is drilled such that the shorter axis of the anchor will fit through the diameter of the hole, with the longer axis of the anchor being parallel to the axis of the drilled hole. After deployment in to the cancellous bone, the anchor is rotated 90B so that the long axis is aligned perpendicularly to the axis of the hole. The suture is pulled, and the anchor is seated up against the inside surface of the cortical layer of bone. Due to the mismatch in the dimensions of the long axis of the anchor and the hole diameter, the anchor cannot be retracted proximally from the hole, thus providing resistance to pull-out. These anchors still suffer from the aforementioned problem of eyelet design that stresses the sutures.
Still other prior art approaches have attempted to use a xe2x80x9cpop rivetxe2x80x9d approach. This type of design requires a hole in the cortical bone into which a split shaft is inserted. The split shaft is hollow, and has a tapered plug leading into its inner lumen. The tapered plug is extended out through the top of the shaft, and when the plug is retracted into the inner lumen, the tapered portion causes the split shaft to be flared outwardly, ostensibly locking the device into the bone.
Other methods of securing soft tissue to bone are known in the prior art, but are not presently considered to be feasible for shoulder repair procedures, because of physicians"" reluctance to leave anything but a suture in the capsule area of the shoulder. The reason for this is that staples, tacks, and the like could possibly fall out and cause injury during movement. As a result of this constraint, the attachment point often must be located at a less than ideal position. Also, the tacks or staples require a substantial hole in the soft tissue, and make it difficult for the surgeon to precisely locate the soft tissue relative to the bone.
As previously discussed, any of the anchor points for sutures mentioned above require that a length of suture be passed through an eyelet fashioned in the anchor and then looped through the soft tissues and tied down to complete the securement. Much skill is required, however, to both place the sutures in the soft tissues, and to tie knots while working through a trocar under endoscopic visualization.
There have been attempts to solve some of the problems that exist in current anchor designs. One such approach is disclosed in U.S. Pat. No. 5,324,308 to Pierce. In this patent, there is disclosed a suture anchor that incorporates a proximal and distal wedge component having inclined mating faces. The distal wedge component has two suture thread holes at its base through which a length of suture may be threaded. The assembly may be placed in a drilled hole in the bone, and when tension is placed on the suture, the distal wedge block is caused to ride up against the proximal wedge block, expanding the projected area within the drilled hole, and locking the anchor into the bone. This approach is a useful method for creating an anchor point for the suture, but does not in any way address the problem of tying knots in the suture to fix the soft tissue to the bone.
The problem of placing sutures in soft tissues and tying knots in an endoscopic environment is well known, and there have been attempts to address the problem and to simplify the process of suture fixation. One such approach is disclosed in U.S. Pat. No. 5,383,905 to Golds et al. The patent describes a device for securing a suture loop about bodily tissue that includes a bead member having a longitudinal bore and an anchor member adapted to be slidably inserted within the bore of the bead member. The anchor member includes at least two axial compressible sections which define a passageway to receive two end portions of a suture loop. The axial sections collapse radially inwardly upon insertion of the anchor member within the bore of the bead member to securely wedge the suture end portions received within the passageway.
Although the Golds et al. patent approach utilizes a wedge-shaped member to lock the sutures in place, the suture legs are passing through the bore of the bead only one time, in a proximal to distal direction, and are locked by the collapsing of the wedge, which creates an interference on the longitudinal bore of the anchor member. Also, no provision is made in this design for attachment of sutures to bone. The design is primarily suited for locking a suture loop, such as is used for ligation or approximation of soft tissues.
A prior art approach that includes tissue attachment is described in U.S. Pat. No. 5,405,359 to Pierce. In this system, a toggle wedge is comprised of a two piece structure comprising a top portion characterized by the presence of a barbed tip and a bottom portion. The suturing material extends through apertures in each of the two toggle portions, and is maintained in position by means of a knot disposed in the suture at a lower edge of the bottom toggle portion. To anchor the suture into adjacent soft tissue, the two toggle portions are rotated relative to one another, as shown for example in FIG. 33. The disclosure states that the device could be used to anchor suture in bone, as well as soft tissue, if two embodiments are utilized in tandem. However, the system is disadvantageous in that it is complex, difficult to manipulate, and still requires the tying of a knot in the suture.
Another approach that includes bone attachment is described in U.S. Pat. No. 5,584,835 to Greenfield. In this patent, a two part device for attaching soft tissue to bone is shown. A bone anchor portion is screwed into a hole in the bone, and is disposed to accept a plug that has been adapted to receive sutures. In one embodiment, the suture plug is configured so that when it is forced into its receptacle in the bone anchor portion, sutures that have been passed through an eyelet in the plug are trapped by friction between the wall of the anchor portion and the body of the plug portion.
Although there is some merit to this approach for eliminating the need for knots in the attachment of sutures to bone, a problem with being able to properly set the tension in the sutures exists. The user is required to pull on the sutures until appropriate tension is achieved, and then to set the plug portion into the bone anchor portion. This action increases the tension in the sutures, and may garrot the soft tissues or increase the tension in the sutures beyond the tensile strength of the material, breaking the sutures. In addition, the minimal surface area provided by this anchor design for pinching or locking the sutures in place will abrade or damage the suture such that the suture""s ability to resist load will be greatly compromised.
A disclosure that incorporates bone attachment and eliminates knot tying is set forth in U.S. Pat. No. 5,702,397 to Goble et al. One embodiment, in particular, is shown in FIG. 23 of that patent and includes a bone anchor that has a threaded body with an inner cavity. The cavity is open to one end of the threaded body, and joins two lumens that run out to the other end of the threaded body. Within the cavity is disposed a gear, journaled on an axle. A length of suture is threaded through one lumen, around the gear, and out through the other lumen. A ball is disposed within the cavity to ride against a tapered race and ostensibly lock the suture in place. What is not clear from the patent disclosure is how the force D shown as the tension in the suture would lock the ball into the race. Although this embodiment purports to be a self-locking anchor adapted for use in blind holes for fixing sutures into bone, the construct shown is complicated, and does not appear to be adequate to reliably fixate the suture.
U.S. Pat. No. 5,782,863 to Bartlett discloses a suture anchor including bone attachment, which simply comprises a conical suture anchor having an anchor bore through which a length of suture is threaded. The anchor is inserted into a bore within a portion of bone using an insertion tool having a shape memory insertion end. As the anchor is inserted, because of its conical shape, it will re-orient itself by rotating in order to fit into the bore, bending the end of the insertion tool. However, once the proximal edge of the bone anchor enters cancellous bone, the shape memory insertion end of the insertion tool will begin resuming its natural straight orientation, thus rotating the anchor back into its original orientation. The corners of the conical body thus protrude into the soft cancellous bone, and the anchor body is prevented from exiting proximally from the bone bore through the hard cortical bone. The insertion tool is then removed.
The Bartlett patent approach, while innovative, is disadvantageous to the extent that it involves the use of a unique and complex insertion tool, and can be difficult to deploy. It also does not permit suturing of the soft tissue prior to anchoring the suture to bone, and thus does not permit tensioning of the suture to approximate the soft tissue to bone, as desired, at the conclusion of the suturing procedure. Additionally, in preferred embodiments, the suture is knotted to the anchor, a known disadvantage.
Yet another prior art approach is disclosed in U.S. Pat. No. 5,961,538 to Pedlick et al. In this patent, a wedge shaped suture anchor system is described for anchoring a length of suture within a bore in a bone portion, which comprises an anchor body having an offset suture opening for receiving the length of suture therethrough, and for creating an imbalance in the rotation of the device as it is inserted. A shaft portion is utilized to insert the wedge-shaped anchor body into the bone bore. Once the anchor body is in cancellous bone, below the cortical bone layer, the shaft is pulled proximally to cause the anchor body to rotate, thereby engaging the corners of the anchor body with the cancellous bone. The shaft then becomes separated from the anchor body, leaving the anchor body in place within the bone.
The Pedlick et al. approach is conventional, in that the suture is attached to desired soft tissue after it is anchored within the bone. Consequently, there is no opportunity to tension the suture, as desired, to optimally approximate the soft tissue to the bone upon completion of the surgical procedure. Additionally, the approach is complex and limited in flexibility, since the suture is directly engaged with the bone anchoring body. There is also the possibility that the bone anchoring body will not sufficiently rotate to firmly become engaged with the cancellous bone before the insertion tool breaks away from the anchor body, in which case it will be impossible to properly anchor the suture.
U.S. Pat. No. 6,056,773 to Bonutti discloses a suture anchoring system which is somewhat similar to that disclosed by Pedlick et al. A cylindrical suture anchor body is provided which is insertable into a bone bore, using a pusher member which pushes distally on the anchor body from a proximal direction. As the anchor body proceeds into the bone bore, below the cortical bone surface, the suture extending through the lumen of the anchor body applies a proximal tensile force on the anchor body, to cause the anchor body to rotate relative to the pusher member, thereby anchoring the anchor body in cancellous bone. Of course, this system has similar disadvantages to those of the Pedlick et al. system, and requires the suture to be directly engaged with the bone anchoring body.
What is needed, therefore, is a new approach for repairing the rotator cuff or fixing other soft tissues to bone, wherein both the bone and suture anchors reside completely below the cortical bone surface, there is no requirement for the surgeon to tie a knot to attach the suture to the bone anchor, and wherein suture tension can be adjusted and possibly measured. The procedure associated with the new approach should better for the patient than existing procedures, should save time, be uncomplicated to use, and be easily taught to practitioners having skill in the art.
The present invention solves the problems outlined above by providing innovative bone anchor and connective techniques which permit a suture attachment which lies entirely beneath the cortical bone surface, and which further permit the attachment of suture to the bone anchor without the necessity for tying knots, which is particularly arduous and technically demanding in the case of arthroscopic procedures. In particular, the present invention employs a uniquely advantageous handle actuator which facilitates a convenient and efficient procedure for the medical practitioner.
More particularly, there is provided a bone anchor insertion device, comprising a handle, a nosepiece connected to a distal end of the handle, a bone anchor connected to the nosepiece, and an actuator disposed on the handle for deploying the bone anchor, which suture is also fixed to a portion of soft tissue to be attached to a portion of bone. Advantageously, a suture ratchet or tensioning mechanism is disposed in the handle for tensioning suture which is associated with the bone anchor. This mechanism permits precise tensioning, while also permitting one-handed operation, thereby allowing the practitioner to use his or her other hand for other activities, such as camera operation or the like.
In a preferred embodiment, the suture tensioning mechanism comprises a suture knob and a suture ratchet wheel, wherein the suture knob is rotatable to rotate the suture ratchet wheel. The suture ratchet wheel includes a suture fixation slit disposed therein for receiving a free end of the suture. The bone anchor comprises a tubular body which is adapted to received the suture therethrough.
In another aspect of the invention, there is provided a bone anchor insertion device, comprising a handle, and a nosepiece connected to a distal end of the handle, wherein the nosepiece comprises an outer tube having a suture opening formed in its distal end and an inner tube disposed coaxially within the outer tube. The inner tube includes a longitudinal slot or opening therein, and is fixed relative to the outer tube. A pull tube is provided, which is insertable into the inner tube. A bone anchor is disposed on the pull tube, which includes a laterally deployable member for engaging adjacent bone matter to secure the bone anchor in the bone matter. The inventive device further comprises an actuator disposed on the handle for pulling the pull tube proximally to deploy the laterally deployable member of the bone anchor by engaging the laterally deployable member with a distal end surface of the inner tube. Preferably, the laterally deployable member comprises a toggle ring member.
In preferred embodiments, the inventive bone anchor insertion device further comprises a suture immobilizing member which is associated with the bone anchor for immobilizing a length of suture situated within the bone anchor. The suture immobilizing member, preferably a suture plug, is connected to a distal end of the pull tube, so that further actuation of the actuator on the handle after deployment of the laterally deployable member of the bone anchor causes the suture immobilizing member to move proximally to engage and immobilize the length of suture. A tab is disposed at a distal end of the pull tube for attaching the bone anchor to the pull tube, which tab is designed to break upon continued proximal movement of the pull tube once the laterally deployable member has been completely deployed, so that further proximal movement of the pull tube causes the suture immobilizing member to move proximally.
In still another aspect of the invention, a method for making an orthopedic repair, by re-attaching a portion of soft tissue to a portion of adjacent bone, using a bone anchor insertion device comprising a handle and a nosepiece attached to a distal end of said handle, is described. This method comprises steps of:
a) passing a length of suture through the portion of soft tissue so that a loop of suture is embedded therein;
b) passing a free end of the length of suture through the nosepiece, a bone anchor disposed thereon, and the handle; and
c) securing the free end of the length of suture to a suture tensioning mechanism in the handle. Further inventive steps include:
d) locating the bone anchor so that it lies beneath a cortical bone surface of the portion of adjacent bone, preferably by moving the bone insertion device into the vicinity of the repair site through a trocar or the like;
e) deploying the bone anchor so that it remains in place beneath the cortical bone surface; and
f) actuating the suture tensioning mechanism to tension the length of suture, thereby approximating the soft tissue portion to the adjacent bone portion as desired.
In a preferred method, the bone anchor insertion device further comprises a pull tube disposed in the nosepiece, and an actuator on the handle for moving the pull tube proximally a desired distance. The bone anchor deployment step further comprises actuating the handle actuator to move the pull tube proximally, until a laterally deployable portion of the bone anchor abuts a mandrel surface on the nosepiece and is thereby forced to laterally deploy. Subsequent to the bone anchor deployment step, a connection between the bone anchor and the pull tube fractures upon continued proximal movement of the pull tube.
Preferably, the bone anchor insertion device further comprises a suture plug attached to a distal end of the pull tube for immobilizing suture within the bone anchor. Thus, the inventive method further comprises a step of continuing to actuate the handle actuator, to thereby move the pull tube proximally, to thereby move the suture plug proximally to immobilize suture within the bone anchor. Then, to complete the procedure, the bone anchor insertion device is separated from the bone anchor and suture plug, the bone anchor insertion device is withdrawn from the repair site, and the suture is trimmed off to complete the repair. The entire method may then be repeated as many times as desired in order to create additional attachment points between the portion of soft tissue and the bone portion, in order to improve the integrity of the effected repair.
In yet another aspect of the invention, there is described a method for making an orthopedic repair, by re-attaching a portion of soft tissue to a portion of adjacent bone, using a bone anchor insertion device comprising a handle and a nosepiece attached to a distal end of said handle. This method comprises the steps of:
a) passing a length of suture through the portion of soft tissue so that a loop of suture is embedded therein;
b) inserting a pull tube, on which is disposed a bone anchor having a laterally deployable member, into the nosepiece;
c) passing a free end of the length of suture through the nosepiece, the bone anchor, and the handle, using snares;
d) locating the bone anchor so that it lies beneath a cortical bone surface of the portion of adjacent bone; and
e) actuating an actuator on the handle to move the pull tube proximally, until the bone anchor is engaged with a mandrel surface on the nosepiece and the laterally deployable member is forced to deploy. In preferred approaches, the method further comprises steps of:
f) tensioning the length of suture to approximate the portion of soft tissue to the adjacent portion of bone, as desired;
g) continuing to actuate the actuator on the handle to further move the pull tube proximally, to thereby move a suture plug attached to a distal end of the pull tube proximally to engage and immobilize suture disposed in the bone anchor,
h) separating the bone anchor insertion device from the bone anchor and suture plug;
i) withdrawing the bone anchor insertion device from the repair site; and
j) trimming off the suture to complete the repair.
The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawing.